The swine flu crisis has spotlighted the close connection between Silicon Valley and Mexico, where several valley companies maintain production and research centers.

None of the local companies with offices there — including Hewlett Packard, Intel, Cisco, Google, Flextronics and Sanmina/SCI — reported any cases of flu among their employees. All said they were monitoring the situation closely.

The companies’ responses ranged from closing Mexico City sales offices to imposing restrictions on travel to and from Mexico. All were educating staff on how to prevent the spread of the illness.

Guadalajara, where several Silicon Valley companies have major operations, has had no reported cases of swine flu, but large public gatherings have reportedly been ordered shut down for 10 days. The illness has hit Mexico City the hardest.

“There’s a significant amount of back and forth” between Guadalajara and Silicon Valley, said Kevin Gallagher, a Boston University professor and author of a recent book on foreign high-tech investment in Mexico. For HP, Guadalajara is a “significant hub,” he said.

HP has more than 1,500 employees in Mexico, according to a company Web site, and Gallagher said HP’s Spanish language call center is in Guadalajara.

A spokeswoman said the company has taken a number of “preventive measures” to help stem the spread of the virus. Asked if any employees had caught the illness, HP declined to comment.

Google shut its Mexico City sales office out of “an abundance of caution,” a company representative reported.

Flextronics, whose U.S. operations are based in Milpitas, has a major operation in Guadalajara. It has imposed travel restrictions to Mexico and asked employees returning from Mexico to work at home for a period of time before returning to work. It has also increased cleaning schedules and is using medical personnel to tell employees how to prevent the virus from spreading.

The firm is screening visitors from Mexico; proposed visits are being considered on a case-by-case basis.

Cisco said it is keeping its Mexico City office open but is restricting nonessential travel to Mexico and is “closely monitoring the situation to understand the implications for our employees, customers and business.”

Intel has a design center in Guadalajara that employs about 400 people, and sales offices in Monterrey and Mexico City that employ about 40 people. A spokesman said it was monitoring the situation using a system of contacts with global health organizations established during the SARS and Avian flu epidemics that struck Asia in 2003 and 2004.

Sanmina/SCI of San Jose has a major facility in Guadalajara, and it said it is working with local health officials.

As social media companies wrestle with how to police dangerous health misinformation on their platforms, Pinterest has taken an extreme approach: blocking search results related to vaccinations, whether the results are medically accurate or not.